This invention relates to display devices and, more particularly, to miniature cathode ray tubes (CRTs) which have semiconductor targets. These would be especially useful in projection display applications where high brightness is required.
In our co-pending patent application Ser. No. 453,577 filed on Dec. 27, 1982 now U.S. Pat. No. 4,539,687 issued on Sept. 3, 1985 we describe in considerable detail the development of the semiconductor laser CRT. In this device the target is a semiconductor which is scanned by the e-beam to generate a coherent light beam which radiates from the region of the semiconductor where the electrons are absorbed. The position of the light beam is varied by scanning the e-beam.
Generating light (radiative recombination of electrons and holes) directly by means of e-beam absorption, however, is not nearly as efficient as by means of current injection across a p-n junction. But localized current injection requires precisely defined electrodes and complex drive electronics. Consequently, it would be a formidable task to use such a method to address the necessary 10.sup.5 -10.sup.6 points in a two-dimensional, high resolution spatial pattern required for a display.